Power consumption
We like to test power draw under load by running a real game rather than a synthetic worst-case, power-hog application. This time around, we chose Arkham City to generate that load. Turns out that game induces higher power draw than Skyrim, which we've used in the past, or Max Payne 3.

Forgive me for leaving out the two older cards here. Time limits prevented us from testing them for power and noise.

For the unfamiliar, the Radeon HD 7900 series has the ability to drop into a special low-power state, called ZeroCore Power, when the display goes into power-save mode. In this state, the GPU's power draw drops to just a few watts, and the video card's cooling fans stop spinning. That's why the Radeons are so much more efficient in the first set of results above. Otherwise, at idle, the GPUs are more or less at parity.

Interesting. These results are pretty different from what we saw when we used Skyrim to generate the load. Really didn't expect to see the stock 7970 drawing less power than the GeForce GTX 680. We may have to use multiple games next time around, if time permits.

Regardless, the 7970 GHz Edition draws quite a bit more power than the stock 7970.

Noise levels and GPU temperatures

ZeroCore power confers a slight advantage on the Radeons in the noise department when the display is off. Otherwise, the stock coolers from AMD and Nvidia are pretty evenly matched, and the custom coolers from XFX and Zotac are a bit louder at idle.

The big winners here are the two Zotac cards, whose triple-slot cooler manages to maintain by far the lowest temperatures and the lowest noise levels of the bunch. Our 7970 GHz Edition review unit is pretty loud. The saving grace is that, as we've noted, you're not likely to see this exact card on store shelves. The third-party coolers from AMD's various partners will hopefully be quieter, although they will have quite a bit of heat to dissipate, given the 7970 GHz Edition's additional power draw.